Vermeer SC252 Stump Grinder Clutch Problem (I think)

[bdoff]

I have a 1998 Vermeer SC252 stump grinder with a 25 hp Kohler motor and a Greenteeth setup. Machine has 525 hours on it and I believe my clutch is going bad, and I need a little help.

When I grind pine stumps or fresh green stumps the cutter wheel will grab and stop, and I hear an unbelievable screetching sound come from the clutch, I believe. Possibly from the belts? But the belts do not seem to show signs of slipping (not glazed or anything like that). In dead wood, the machine runs like a top...no issues, just rips 'em right out.

In the fresh green stumps or pine stumps, after grinding for long periods even using small swipes, I notice a loss in torque. I've taken the covers off and tried to witness the clutch itself squealing, but it doesn't seem to start doing it until you've been grinding for about 30 minutes...then it just seems to lose all torque.

Anyone else ever have this problem? Anything else I can check for? I replaced the belts running from the clutch to the front of the machine with a single power V belt, but that's all I've done since I bought it. I've called a couple Vermeer dealers and the clutch is $454, so I want to make sure that's what the problem definitely is before I replace that. Just looking for any suggestions of anything I should try first. <this is an eletric clutch>

Thanks in advance for any help!

 

[l2edneck]

sounds like normal slip to me.

 

[bdoff]

its definitely not normal slip.. its hardly not even the same machine it was last year.... i could grind and not hear the squeal at all.. and now it seems to squeal all the time and lose power. also, the belts are tensioned properly. :help:

 

[gr8scott72]

also, the belts are tensioned properly. :help:

Doesn't sound like they are.

 

[BC WetCoast]

Sounds to me like your belts are slipping.

I find that you need to have sharper teeth to cut green stumps than dry stumps, where even dull teeth can blow the wood apart. Are your teeth sharp?

Also I find that in pine, changes in grain direction in the root crown can slow down the cutting efficiency. The only thing I have found that helps this is to remove extra chips from the hole, so there is less friction for the wheel when you are cutting deep.

 

[bdoff]

Thanks alot for the replies guys, I'll be out of town all week and I'll check this stuff this weekend when I get home. I appreciate the advice!

 

[arbor pro]

When I followed factory specs for tightening my belts, I would get slippage on green stumps. I now tighten them manually without a torque wrench and have gotten no slippage with no additional bearing, clutch or belt wear (so far at least). I try to tighten the cutter wheel belt until it has about 1/2" deflection when I push on it hard. I tighten the jackshaft a little less (about 3/4" deflection.

It works for me. I can't stand belt slippage. I'd rather replace other parts more often if overtightening of the belts results in more wear elsewhere. JMO.

 

[scouse]

If its the clutch you should be able to hear it slip when you engage it (its more like a metalic grinding noise than belt squeal)
Hope it helps, had to replace the clutch on mine was a bout £350 ($700 approx :jawdrop: )

 

[Bigstumps]

You mentioned you replaced the single belts with a powerband. I don't think you can do this - the spacing and the top land between the grooves on those Ogura clutches are not standard and will not let a powerband belt ride down where is supposed to. Even though you have the correct static tension I believe you are tightening the belts on the webbing between the bands and not getting the proper wedging action needed on a V Belt to transmit the power.

Go back to a couple single belts and see if this doesn't solve your problem.

 

[Mike W]

Have you adjusted your clutch? On our 5 252's at work, all of them have adjustments on the clutch. There should be studs on the outside of the clutch and a small window to put a feeler gauge in. I can look at the manual at work on Monday if you need me to to get the right clearance numbers for you or pics if you want.
Mike

 

[bdoff]

well.. i did what bigstumps suggested and went back to two belts insted of the one V belt made a big difference. but still not up to par in my opinion



mike w.... i was unaware that i could adjust my clutch. any info you can pass on pics and specs would be greatly appreciated.


thanks to all and keep the info flowing

 

[Mike W]

I'll get pics tomorrow, but there's supposed to be .012 - .024 clearance. If yours is adjustable, there will be 3 1/4" bolts with a spring and lock nut on each one, put a feeler gauge in the "window" next to it and work your way around until there all 3 the same. Some of the older ones are not adjustable though.